Discovery of excimer laser surgery laid foundation for PRK, LASIK
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To celebrate the 40th anniversary of Healio/Ocular Surgery News, we are looking back at major developments in ophthalmology. In this submission to the 40th anniversary collection on Healio/OSN, James J. Wynne, PhD, reflects on the discovery of laser refractive surgery.
On Nov. 27, 1981, the day after Thanksgiving, Dr. Rangaswamy Srinivasan brought Thanksgiving leftovers into the IBM Thomas J. Watson Research Center, where he irradiated turkey cartilage with 10-nanosecond pulses of 193-nm light from an argon fluoride (ArF) excimer laser. This far-ultraviolet irradiation produced a clean-looking “incision,” as observed through an optical microscope.
Subsequently, Srinivasan and his IBM colleague, Dr. Samuel E. Blum, carried out further irradiation of cartilage samples. Srinivasan then gave a sample to me, another IBM colleague, and for comparison, I irradiated it with 10-nanosecond pulses of 532-nm light from a Q-switched frequency-doubled Nd:YAG laser. This irradiation did not incise the sample; rather, it created a burned, charred region of tissue. Realizing that we had discovered something novel and unexpected, we wrote an invention disclosure, describing multiple potential surgical applications. We anticipated that the absence of collateral damage to the tissue underlying and adjacent to the incision produced in vitro would result in minimal collateral damage when the technique was applied in vivo. The ensuing healing would not produce scar tissue. This insight, a radical departure from all other laser surgery, was unprecedented and underlies the subsequent application of our discovery to laser refractive surgery.
While IBM was preparing a patent application, we were constrained from discussing our discovery with people outside IBM. After the patent application was filed in December 1982, we submitted a paper describing our discovery to the trade publication Laser Focus. The publication of the issue containing the paper coincided with the 1983 Conference on Lasers and Electro-Optics (CLEO), held in Baltimore, where, on May 20, Dr. Srinivasan gave an invited talk entitled “Ablative photodecomposition of organic polymer films by far-UV excimer laser radiation.” His presentation included the first public disclosure that the excimer laser cleanly ablated biological specimens, as well as organic polymers.
At this same CLEO 1983 meeting, Dr. Stephen Trokel and Dr. Francis L’Esperance, two renowned ophthalmologists, gave invited talks on applications of infrared lasers to ophthalmic surgery. Trokel knew of ophthalmic conditions, such as myopia, that could be corrected by modifying the corneal curvature. A treatment known as radial keratotomy (RK) corrected myopia by using a cold steel scalpel to make radial incisions at the periphery of the cornea. Upon healing, the curvature of the front surface of the cornea was reduced, thereby correcting myopia. While this technique rarely yielded uncorrected visual acuity of 20/20, the patient’s myopia was reduced. One serious drawback of RK was that the depth of the radial incisions left the cornea mechanically less robust. Trokel speculated that the excimer laser might be a better tool for creating the RK incisions.
Upon learning of the IBM team’s discovery of excimer laser surgery, Trokel, who was affiliated with Columbia University’s Harkness Eye Center in New York, contacted Srinivasan and brought enucleated calf eyes (derived from slaughter) to the Watson Research Center on July 20, 1983. Srinivasan’s technical assistant, Bodil Braren, participated in an experiment using the ArF excimer laser to precisely etch the corneal epithelial layer and stroma of these calf eyes. The published report of this study in American Journal of Ophthalmology is routinely referred to by the ophthalmic community as the seminal paper in laser refractive surgery.
To conduct studies on live animals, the experiments were moved to Columbia’s laboratories. Such experiments were necessary to convince the medical community that living cornea etched by the ArF excimer laser would not form scar tissue at the newly created surface and the etched volume would not be filled in by new growth. The first experiment on a live rabbit in November 1983 showed excellent results; after a week of observation, the cornea was not only free from any scar tissue, but the depression had not filled in. Further histological examination of the etched surface at high magnification showed an interface free from detectable damage.
L’Esperance, also affiliated with Columbia, thought beyond RK and filed a patent application describing the use of excimer laser ablation to modify the curvature of the cornea by selectively removing tissue from the front surface, not the periphery of the cornea. U.S. Patent No. 4,665,913 specifically describes this process, which was later named photorefractive keratectomy (PRK).
Soon, ophthalmologists around the world, who knew of the remarkable healing properties of the cornea, were at work exploring different ways to use excimer lasers to reshape the cornea. Since the FDA granted approval to manufacturers of laser refractive surgery systems in 1995, more than 60 million patients have undergone the procedure to improve their eyesight.
Laser refractive surgery can restore visual acuity to better than 20/20. With refinements in so-called “custom wavefront-guided” laser refractive surgery, many patients undergoing laser refractive surgery achieve visual acuity of 20/12.
The IBM team’s discovery at the end of 1981 laid the foundation for modern PRK and LASIK.
- Reference:
- Trokel SL, et al. Am J Ophthalmol. 1983;doi:10.1016/s0002-9394(14)71911-7.
- For more information:
- James J. Wynne, PhD, can be reached at email: jjwynne@us.ibm.com.
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